The sentence discusses Mr. Hamilton's support for flood victims and his underlying motives. The key contrast is introduced by "seemed $\qquad$ his motives were likely rooted in his need for publicity."
- The phrase "his motives were likely rooted in his need for publicity" implies that his actions were not purely selfless. They had a hidden, self-serving agenda.
- Therefore, the blank must describe how his actions appeared on the surface - which would be the opposite of being motivated by publicity. His actions would seem to be selfless or genuinely caring.

Let's evaluate the options:
- A. miserly: Extremely stingy; mean. This is the opposite of "extensive support."
- B. abashed: Embarrassed, disconcerted, or ashamed. This describes a feeling, not the nature of his support.
- C. altruistic: Showing a selfless concern for the well-being of others; unselfish. This perfectly describes how his extensive support would appear on the surface, contrasting with his underlying motive for publicity.
- D. solemn: Formal and dignified; serious. This describes a demeanor, not the quality of his support's motivation.
- E. outlandish: Looking or sounding bizarre or unfamiliar; strange. This doesn't fit the context of motives for support.
- F. philanthropic: Seeking to promote the welfare of others, especially by donating money to good causes; benevolent. This is a strong synonym for "altruistic" and also perfectly describes how his extensive support would appear to be genuinely for the good of others, contrasting with his true motive.

Conclusion:

Both "altruistic" and "philanthropic" mean selfless or charitable, which is how Mr. Hamilton's extensive support would appear on the surface, making the contrast with his underlying publicity motive clear.